Rock & Gem Kids: Considering Clinochlore

This curled gypsum crystal from San Pedro, California, is referred to as ram’s horn selenite.

Chlorite Group
(Mg,Al)6(Si,Al)4O10(OH)8

Clinochlore is in the chlorite group of minerals. Its name comes from the Greek words klino (“to incline”) and chloros (“green”) because it is usually a dark green mineral with tabular crystals that have oblique (inclined) axes. The crystals range from transparent to opaque with a pearly luster.

Shimmery and Silvery Appearance

In addition to the crystal form, it’s also found as foliated (scaly) masses with a chatoyant shimmer that resembles silvery feathers. This form of clinochlore often goes by the trade name seraphinite, or Angel’s Wing Stone. The feather-like sheen brings to mind the seraphim, or three-winged angels that are said to fly around the throne of God. That feather-like patterning is due to mica inclusions.

Clinochlore is formed during processes of low-grade regional and contact metamorphism and is often found in association with metamorphic rocks like schist. It can also form through hydrothermal alteration of other minerals. The crystal form has been found in many parts of the world: the U.S. (Pennsylvania, New York, Vermont), Canada, Italy, Austria, Switzerland, Germany, Turkey, Brazil, Scotland, Sweden, and Russia’s Ural Mountains. The seraphinite form is mined on a commercial scale in a small area of eastern Siberia.

A rough chunk of the seraphinite variety of clinochlore is foliated and holds inclusions of mica.

Seraphinite Is Lapidary Selection

Because of its beautiful chatoyancy, the seraphinite variety of clinochlore is sometimes used as a lapidary stone for cabochons, carvings, and spheres. However, it’s a soft stone (Mohs 2-2.5), which limits its use in jewelry. It is sometimes impregnated with polymers to give it more durability, but still, it’s usually used only for pendants and earrings as opposed to rings or bracelets that might take hard knocks. Like an angel’s wing, it’s beautiful but delicate!

Author: Jim Brace-Thompson

Founder and overseer of the AFMS Badge Program for kids.

He’s also an inductee of the National Rockhound & Lapidary Hall of Fame within the Education Category.

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